Safety pressure tank for liquid storage



June 2, 1936. w. A. SANDBERG SAFETY PRESSURE TANK FOB LIQUID STORAGE Filed Dec. '4, 1933 W. A. SANDBERG 7 INVENTOR 4 ORA/EV Patented June 2, 1936 PATENT OFFICE SAFETY PRESSURE TANK FOR I LIQUID STORAGE William Andrew 'Sandberg, Los Angeles, Calif.,

assignor to Parkhill-Wade, Incorporated, Los Angeles, Calif., a corporation of California Application December 4, 1933, Serial No.'700,7 81

2 Claims. (Cl. 137-21).

' In the handling and storage of such liquids as the lightest petroleum fractions, which boil at atmospheric pressure and temperature, it is a matter of serious difiiculty to gauge a tank in the process of filling and to avoid filling the tank completely. A tank so filled and lacking any space occupied by'compressible gas or vapor is ,in serious danger of rupture, due to liquid expansion resulting from subsequent rise in temperature, which may lead to the sudden escape part or all of its contents and to disastrous fire or explosion.

Even where the liquid with which the tank is "to be filled is of such nature that it may be gauged, the gauging operation is a time-wastin nuisance and carelessness or error on the part a; the operator may cause the tank to be comthe tank shown in Fig. 1;

pletely filled with liquid, incurring the said danger'of the destruction of the tank and the loss of its contents by reason of liquid expansion.

The object of my invention is to provide a tank in which the ullage space is out of communication with the interior of the tank while the filling operation is in progress and in which this space is constantly filled with compressible gas or vapor and cannot by carelessness or oversight become filled withincompressible liquid.-

The objects and advantages of my invention may best be viewed in connection-with the attached drawing, in which:

Q-Fig. 1 is an elevation of a tank suited to the application of my invention,-certain interior arrangements being shown by means of dotted Fig. 2 is an elevation of the right hand end of Fig. 3 is a plan view of the same end of this tank;

Fig. 4 is a detail of the port arrangements in the three-way cock shown at It in Figs. 1, 2,

and 3;

Fig.5 is a detail showing a suggested means for actuating the plug in the three-way cock show in Fig. 4, and

- Fig. 6 is-an enlargement of aportion of Fig. 5.

Referring to the drawing, I0 is any closed tank designed-for the safe working pressure desired, this pressure being variable according to the characteristics of the liquid to be stored or transported. This tank may "optionally be provided with gas vent and liquid drain openings II and II respectively, these openings being no part of the invention and being tightly plugged during normal operation. An outlet pipe l3 provided with any suitable valve I4 is placed in any desired position in the tank, either in,the end as shown or in the bottom sheet.

Within the tank I0, I place a smaller tank or shell l5, this tank being supported in any convenient manner, as by spot welding to the upper side of the outer tank. The shell 15 must be gas tight and must not communicate with the interior of tank ill in any manner whatsoever except through the exterior connections about to be described.

In any convenient position, as on the right hand end of the tank as shown in Fig. 1, I place a valve or valves such, for example, as the threeway, two-port cock shown in Fig. 4 and indicated at It in Figs. 1, 2, and 3. In this cook the nozzle A, may be connected tothe pipe I! by means of which the liquid to be stored is introduced into tank l0; nozzle B is connected to a pipe I8 which is fixed in the wall of tank Ill and affords communication with the interior of such tank, and

nozzle C is connected to a pipe l9 which is sealed.

into the wall of tank l0 and is fixed in the'bottom wall of shell-l5, affording communication with the interior of this shell but not with the interior of tank I0. Port D through the plug is so formed that with the plug inthe position shown by solid lines it will afford free communication between pipes I1 and I8, and port E is so formed that with the plug in the same position pipe l9 will be blanked air.

On rotating the plug a quarter turn counterclockwise the position of the ports will be reversed as indicated indotted lines, pipe I! being blanked off and the interior of the shell I 5 being placed in communication with the interior of tank I0 through pipes I8 and I9 and port E.

When tank I0 is being filled, the plug is rotated to the first position described, in which fill-pipe l! is in communication with the interior of the tank and the ullage shell I5 is sealed away from both tank It and the infiowing liquid and is thus positively maintained full of gas or vapor. When filling has been completed-and this operation may be carried to the point where no more liquid can be forced into the tank under a pressure below its safe working pressure, or until liquid appears at a try-cock placed in the top of the tankthe position of the plug is reversed to that shown by dotted lines, by which change the fill pipe is sealed off and the ullage shell placed in free communication with the interior of tank l0. Liquid may then flow from the tank into the ullage space, which provides the necessary cushion to prevent damage to the tank, and will gradually return to the tank under the pressure of the confined gas or vapor as the contents of the tank are withdrawn.

A plug cock, suitably packed to prevent leakage, is highly suitable for the described purpose, but is subject to the objection that, as ordinarily proportioned, the ports are of such width as compared with the bridge between them that it is possible to place the plug in such a position as to substantially close both the channel between the ullage space and the tank and the channel between the tank and the fill pipe. Such occurrence, following carelessness on the part of the operator after filling the tank, would render the ullage space useless and destroy the value of the shell as a safety device.

In order to obviate this possibility I suggest the means of actuating the plug shown in Fig. 5. In this device the plug is turned by means of a handle 20 having at its end a disc 2! provided with a central hole fitting loosely over a pin 22 projected centrally from the plug end 23, this disc having also an arcuate slot 24 concentric with pin 22 and engaging a pin 25 fixed in the plug end. A rigid arm 26 is laterally projected from the plug end and a similar arm 21 from the exterior body, and between the extremities of these arms a. strong closed coil spring 28 is stretched. The arm 26 comes to rest against stops 29 and 30 suitably placed to bring the ports in the proper positions for use.

It will be seen that when the handle is placed in position and revolved around the central pin, the plug will be revolved forcibly to a point slightly past the center line, from which point it will be carried by the resilience ofthe spring to come to rest against the opposite stop, thus positively preventing it from being left in a partly shifted position. It will be obvious that there are numerous ways in which this object could be accomplished, and that a combination of interconnected valves could be substituted for the cock described to serve the same purpose. I

claim no invention in the use of any specific valve or cook arrangement, but include in the scope of the appended claims any suitable means for reversing the channels for the purpose above described.

The form shown for shell I5 is desirable but not essential. Any portion of the upper part of tank l0 may be partitioned off to form this shell or compartment, or it may be formed outside the main tank and adjacent its upper side. It is essential, however, that the shell or compartment-be so formed and located as to drain completely into the tank through the channel consisting of pipes l9 and I8.

I claim as my invention:

1. In combination: a liquid storage tank, an ullage tank, a pipe arranged for filling said storage tank, and unitary valve means providing the sole means of communication between said filling pipe and saidstorage tank and between said ullage tank and said storage tank and being arranged to positively prevent communication between said filling pipe and said ullage'tank, said valve means and said ullage tank being so positioned as to allow liquid to flow by gravity through said valve means from said'ullage tank into said storage tank.

2. A substantially closed liquid storage tank having a tight compartment formed adjacent the upper side thereof, a pipe arranged for filling said storage tank, and unitary valve means providing the sole means of communication between said filling pipe and said storage tank and between said compartment and said storage tank and being arranged to positively prevent communication between said filling pipe and said compartment, said valve means being so positioned as to allow liquid to flow by gravity through said valve means from said compartment into said storage tank.

WILLIAM A. SANDBERG. 

